Carolyn McCall oversaw the transformation of the Guardian Media Group with the £1bn purchase of Emap's business-to-business magazines, information and events arm.

McCall said the buyout, in a joint deal with private equity firm Apax, would help guarantee the long-term financial security of the Guardian by further diversifying GMG's media interests.

Carolyn McCall. Photograph: Sarah Lee
The group already comprises the Guardian and Observer; the guardian.co.uk network of websites; GMG Radio; regional newspapers including the Manchester Evening News; and Trader Media Group, publisher of Auto Trader, in which Apax already owns a minority stake.

GMG and Apax already had close working ties after the private equity firm paid £675m for a 49.9% stake in Trader Media Group last year.

The former head of GMG's national newspaper division, McCall oversaw the transition of both the Guardian and the Observer to their new Berliner formats and became chief executive two years ago.

McCall is also a member of the Scott Trust, set up in 1936 to safeguard the financial and editorial independence of the Guardian and the owner of Guardian Media Group. McCall has said she wants the Guardian to be the "leading global liberal voice".

She was this year named the Veuve Clicquot businesswoman of the year, praised for having led GMG through a "vast range of change and growth" and for her "forward-thinking attitude, positively embracing innovation in order to anticipate the future".

GMG reported pre-tax profits up 47% to £97.7m in the year to April last year, on turnover up 2% to £716.1m. McCall said it was a "really strong performance" against a "difficult and challenging backdrop".

The Emap deal reduced the proportion of total revenues Guardian Media Group draws from print from about 85% to 65%. The acquisition included a range of more than 20 business-to-business titles including Retail Week, Nursing Times, Broadcast and Screen International; events including the Cannes Lions Advertising Festival and data business including fashion information website WGSN.

McCall has held senior management positions at GMG for more than a decade. She was succeeded as head of the Guardian's national newspaper division by Tim Brooks, former managing director of IPC's Ignite! division and co-founder of industry magazine Media Week.

The past year has seen a new editor at the Observer, with John Mulholland succeeding Roger Alton.

McCall joined Guardian Newspapers as advertising director in 1995, becoming commercial director and then deputy managing director in 1998. She became head of its national newspapers division in 2000 and was awarded an OBE this year for services to women in business.

She resigned as a non-executive director of Tesco earlier this year after the supermarket group launched a legal action against the Guardian.

· To contact the MediaGuardian news desk email editor@mediaguardian.co.uk or phone 020 7239 9857. For all other inquiries please call the main Guardian switchboard on 020 7278 2332.

· If you are writing a comment for publication, please mark clearly "for publication".